Fluidic load regulator

ABSTRACT

A fluidic pressure regulator includes a pair of opposed nozzles connected respectively to a common source fluid supply through individual adjustable pressure dropping resistors. A variable flow load is connected to the junction of one resistor and the related nozzle. The nozzles establish opposing impacting flows with a stagnation or impact flow position adjacent the orifice of the load connected nozzle. The load connected resistor and nozzle define a pressure dividing network to establish a predetermined pressure output without load flow. Load flow tends to drop the load and load nozzle pressures. However, a decrease in the nozzle pressure causes movement of the impact flow toward the related orifice which increases the nozzle and therefore load pressure to maintain a regulated load pressure.

Unit States Lechner, ,lr.

.ltet [191 FLUlllDIC LOAD REGULATOR [75] Inventor: Thomas J. Lechner,Jr., Menomonee Falls, Wis.

[73] Assignee: Johnson Service Company,

Milwaukee, Wis.

[22] Filed: Sept. 29, 1971 [21] Appl. No.: 184,686

[52] US. Cl. 137/824 [51] Int. Cl. FlSc 1/20 [58] lField of Search137/815, 824; 73/37.7

[56] References Cited UNITED STATES PATENTS 3,272,215 9/1966 Bjornsen eta1 137/815 3,279,489 10/1966 Bjornsen et al 137/815 3,340,886 9/.1967Jacobson 73/37.7 X 3,343,459 9/1967 Jacobson 73/37.7 X 3,388,713 6/1968Bjornsen.... 137/815 3,472,255 10/1969 Fox et al l37/8l.5 3,616,80911/1971 Laakaniemi et al. 137/824 X 3,623,497 12/1969 Kaske r l 137/8153,710,421 l/l973 Tooka 73/37.7 X

Primary ExaminerWilliam R. Cline Assistant Examinerlra S. LazarusAttorney, Agent, or FirmAndrus, Sceales, Starke & Sawall [5 7 ABSTRACT Afluidic pressure regulator includes a pair of opposed nozzles connectedrespectively to a common source fluid supply through individualadjustable pressure dropping resistors. A variable flow load isconnected to the junction of one resistor and the related nozzle. Thenozzles establish opposing impacting flows with a stagnation or impactflow position adjacent the orifice I 11 Claims, 4 Drawing Figures SOURCEPRESSURE l l l l l i l l PATENTELUEC 1 01914 SOURGE PRESSURE FIG.'.3

0 304m UJNNOZ INVENTOR. THOMAS J. LECHNER JR.

A I v Jug, Jaw/J Attorneys A G I F 2 3 PRESSURE (PSIG) FLUIDIC LOADREGULATOR BACKGROUND OF THE INVENTION This invention relates to afluidic load regulator and particularly to a pressure type regulator forincorporation in fluidic control or drive systems and the like.

Fluidic devices and interrelated industrial control systems have beendeveloped to provide a pure fluid or essentially pure fluid system whilemaintaining many of the advantages and the versatility of electrical andelectronic control systems. Thus, pure fluidic amplifiers and modulatorscan be constructed without moving mechanical parts through the use ofinteracting fluid streams. Such fluidic devices have certain advantagesover electrical devices, particularly in environments where theelectrical systems are adversely affected by spurious magnetic andelectrical signals and must be especially constructed or operated.Further, pneumatic and similar operating systems can be readilyconnected to fluidic controls.

In many pneumatic and other fluid controls, a pressure signal deliveredto a load or consuming device may require regulation such that theoutput pressure is essentially independent of the output or load flow.The output pressure variation with supply or source pressure variationis also preferably minimized. Although mechanical load flow regulatorsare well-known in the art there is a need for a fluidic regulator.

SUMMARY OF THE PRESENT INVENTION The present invention is particularlydirected to a fluidic flow regulator which establishes an outputpressure which is essentially independent of the load flow. Thepreferred construction of the invention also produces an equalpercentage variation of the output pressure with a variation in sourceor supply pressure.

Generally, in accordance with the present invention, the pressureregulator includes a pair of stream forming means interconnected to acommon pressure source means. The stream forming means are mounted inopposed and spaced relationship to establish a pair of opposed impactingstreams with the impact position therebetween. The connection to thecommon pressure source means includes a flow resistance means between,at least, one of the stream forming means and the source means, with theoutput or load interconnected into the system between the resistancemeans and the corresponding stream forming means. Applicant has foundthat by proper selection of the supply connections and the streamforming means characteristics, the impacting balance or stagnationposition is formed in a region wherein a very high rate of change insuch position occurs with variation in the output or load pressure, suchthatthe stream forming means effectively undergoes a significantimpedance change for very small pressure changes. With this operationand characteristic, any increase or decrease in load flow results in aminute change in the output pressure with a corresponding inverse flowthrough the associated stream forming means to maintain an essentiallyconstant output load pressure. Thus, the load pressure remainsessentially constant and independent of normal fluctuations in loadflow. Further, although the regulator will not maintain regulations withvariations in supply pressure, it does provide equal percentageregulation such that the'load variation is a corresponding percentageand not directly equal to the supply pressure change.

In accordance with the particularly novel construction, the presentinvention employs a pair of opposed nozzles connected respectively to acommon source fluid supply through individual pressure droppingresistors. The load is tapped or connected to the junction of one loadresistor and the related load nozzle. The load resistor is preferablyadjustable and is adjusted to establish the desired output pressure witha minimum load flow and with the opposed nozzle cut off. The nozzlediameters are so selected that they will pass the difference between themaximum and minimum load flow at the design pressure to be regulated.The second nozzle is then connected to the source through its resistorand adjusted to establish a stagnation or impact position just outwardlyfrom or slightly spaced from the ori' fice of the load nozzle. The loadresistor and the nozzle define a pressure dividing network (similar to avoltage divider in electrical circuits) to establish a predeterminedpressure output without load flow. If load flow is increased, it wouldtend to drop the load pressure. This in turn would tend to decrease theload nozzle pressure. However, a decrease in the nozzle pressure causesmovement of the impact flow toward the related load nozzle, therebytending to block said nozzle and automatically provide a regulatingeffect.

Applicant has found that the present pressure regula tor providesexceptional regulation over a selected operating range which can bedirectly and practically applied in fluidic flow systems. The load flowis directly taken from the source through the load resistor and does notpass through a separate regulating or fluidic device and thereby permitsrecovery of output pressure equal to essentially one hundred percent ofthe supply pressure. The output pressure may therefore be selected atany value between reference and supply pressures. The load regulator ofthe present invention only requires twice the total desired flow changerequired by the load. Thus, the air consumed by the load regulator isnot related to the total load flow but only to the desired or permittedchange in load flow.

Further, a very significant advantage which Applicant has obtained withthe present invention is the regulation of relatively low pressurestream flow or output stream flow. Thus with the present invention,regulation of pressures in the range of hundreths of pounds per squareinch or centimeters of water have been reliably attained. To attain asimilar results in the present diaphragm type units or the like wouldrequire impractically large diaphragms. Further the advantage of fluidicsystems of course would also be lost with such sys tems.

The present invention thus provides a fluidic regulator for establishingof the output pressure essentially independent of load flow in arelatively simple and inexpensive construction and with a minimum loadpressure variation with supply pressure variation.

BRIEF DESCRIPTION OF THE DRAWING The drawing furnished herewithillustrates the preferred construction of the present invention in whichthe above advantages and features are clearly disclosed as well asothers which will be readily understood from the description of thepreferred embodiment of the invention.

In the drawing:

FIG. 1 is a schematic illustration of a fluidic system including a flowregulator in accordance with the teaching of the present invention;

FIG. 2 is a diagrammatic illustration of a pair of opposed nozzles shownschematically in FIG. 1;

FIG. 3 is a graphical illustration of the flow characteristics withvarying input nozzle pressures and flow and further showing one loadline; and

FIG. 4 is a graphical illustration of pressure versus flow showing theimpedance curve for a pressure regulator such as shown in FIG. 1.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT Refering to the drawing andparticularly to FIG. 1, a pressure source or supply 1 of a suitableoperating fluid such as gas, liquid or mixtures is shown interconnectedto drive a fluid system load 2 through a pressure regulator 3constructed and connected between the supply 1 and the load 2, inaccordance with the teaching of the present invention. The load 2 isshown with an arrow thereto to indicate that the load flow demand mayvary. The pressure regulator 3 is constructed to maintain an essentiallyconstant pressure across the system load 2 with such normal variationsin the output load flow. In accordance with the present invention thepressure regulator is a pure fluid device based on the impacting streamconcept and employing an impact modulator 4, which is schematicallyshown in FIG. 1 and diagrammatically illustrated'in FIG. 2. The source 1and load 2 may provide and consume any suitable fluid medium butadvantageously employs air which is readily available and references toatmosphere. The system is hereinafter described as a pneumatic system.

The impact modulator 4 includes a pair of opposed nozzles 5 and 6 whichin the illustrated embodiment of the invention have similar opposedstream forming orifices 7 which are not necessarily of the samediameter. The nozzle 5 is connected to the supply 1 in series with aload connected resistor 8, which may be adjustable for setting of theregulated pressure. The nozzle 6 is similarly connected to the supply inseries with a dropping resistor 9 which is also shown to be adjustable.The nozzles are mounted with the-orifices 7 in directly opposed alignedrelationship as shown in FIG. 2 for maximum regulation, but could beskewed or canted if desired. The connection to the supply through theresistors 8 and 9 establishes a pair of opposing streams l and 11 whichimpact, within the space between the two nozzles 12, is connected toatmosphere or some other convenient reference pressure to allow freeexiting of the impacting streams. The reference pressure must be lessthan the desired regulated pressure.

Referring to FIG. 1, the load 2 is connected to the junction of theresistor 8 and the nozzle such that the output pressure is directlyrelated to the division of the supply pressure established by the flowthrough these respective elements.

Thus, if the nozzle 5 is completely blocked to prevent any flowtherethrough, all the flow through resistor 8 flows through load 2. Thisrepresents the maximum flow that the load can regulate to and thepressure is equal to the supply pressure less the drop across resistor8, thus determining the value of resistor 8.

If the nozzle 5 is completely unrestricted, the flow through resistor 8divides between load 2 and nozzle 5. This represents the minimum flowthat the load can pass at the regulated pressure and thus determines thesize of nozzle 5.

For example, referring particularly to FIG. 3, the flow characteristicfor nozzle 5 is shown by trace 13. If the load flow is reduced, thenozzle flow increases and the pressure increases at the junction of therestrictor or resistor 8 and the nozzle 5 in accordance with trace 13.The load pressure equals the nozzle pressure and thus also increases inaccordance with the curve 13. For any given supply, the load pressureintercepts the trace 13 and will vary with flow in accordance with aload line determined by the resistor 8, such as shown at 14 in FIG. 3.

In the presence of the opposing stream 10 from nozzle 6 thecharacteristic is further controlled by the relative strength of the twostreams 10 and 11. In FIG. 3, traces 15 through 18 are illustrated fordifferent preset pressures at nozzle 6, and are typically taken from afamily of curves related to incremental pressure changes betweenpressures from 2 to 10 p.s.i.g. in nozzle 6. With the nozzle 6 at apressure of 2 pounds per square inch, there is a negative flow throughthe nozzle 5 as shown by the lower portion of trace 15 until such timeas the opposed nozzle pressure 5 equals the set pressure at nozzle 6.When the pressures are just equal there is a zero load flow through thenozzle 5 indicating that the impact position is adjacent the orifice 7with all flow of nozzle 6 exiting to the reference. As the nozzle 5pressure increases, the interaction with the nozzle orifice 7 at nozzle5 is such that the system exhibits a characteristic of a very extremeimpedance change for very minute pressure changes. Thus, a very slightincrease in the pressure at nozzle 5 establishes a very rapid andsubstantial increase in the flow through nozzle 5 which is limited bythe nozzle characteristics with zero pressure in nozzle 6. The devicemay be considered to be functioning in the manner of a zener diode in anelectronic regulating circuit except that the impedance characteristicoccurs at the point where the nozzle pressures are essentially equalrather than as a result of the inherent physical characteristic of thematerial of an element. Thus a very small change in the pressure atnozzle 5 is accompanied with substantial variations in flow, producingextremely high gain. Graphically, each of the traces 15 18 include anessentially straight line change in flow to the intersection of the flowcharacteristic line 13. The resistor 8 is selected or adjusted fornozzle 5 such that the nozzle pressure equals the desired load pressurewith minimum or zero load flow and with the nozzle 6 cut off. Further,the orifice of nozzle 5 is selected to pass the difference between themaximum load flow and minimum or zero flow, as shown in FIG. 3 by theintersections of the traces l5 18 inclusive with the curve 13.

In the present invention, the dropping resistor 9 is selected toestablish the necessary pressure in nozzle 6 which will create animpacting point just outwardly of the orifice 7 of the nozzle 5, forexample, as illustrated in FIG. 2. The resistors 8 and 9 thus establishthe common intersection of the load line 14 with the nozzlecharacteristic curve 13 and the desired nozzle characteristic curves 1518.

In operation, if there is an increase in load flow, a very minute andpractical insignificant change in the pressure of nozzle 5 provides acorresponding decrease in the nozzle flow to keep the net flow throughthe regulator and the load constant with an essentially con stant loadpressure.

The impact modulator 4 provides a continuous modulation similar to thefunction of a diaphragm pressure regulator with the stream from nozzle 6functioning as the lid or diaphragm unit overlying the nozzle 5.However, the present invention allows operation and control regulationof pressures at relatively low values and in order of hundreths ofpounds per square inch in a practical construction. Although it ispossible to generally accomplish similar results with diaphragm units,the diaphragm must be extremely large and is therefore impractical.Further, the present invention provides a simple and inexpensive meansof completely eliminating the mechanical features heretofore employed inpressure regulators and provides a load regulating flow wherein the loadflow does not pass through a fluidic device before being applied to theload.

In FIG. 4-, typical regulated pressure curves 19 22 are shown. Theembodiment of the invention for obtaining such curves was generally asshown in FIG. 1 with the opposing nozzles having orifices essentially0.025 inches in diameter with a gap or spacing therebetween of 0.031inches. Air was employed to form the stream from a supply pressure of 20p.sig. (pounds per square inch gauge). The restrictors or resistors 8and 9 and the load 2 were made adjustable as diagrammatically shown inFIG. 1. The fluid resistors 8 and 9 were set to establish regulatedpressures of l, 2, 5 and 10 p.s.i.g. The load flow was then varied asshown in FIG.

' 4. Thus for 1 p.s.i.g. an essentially constant output pressure wasmaintained over the range of O to 100 cubic inches per minute, as shownby trace 19. When the regulated pressure was raised respectively to 5and I p.s.i.g. by readjustment of the resistors 8 and 9, a similarcharacteristic resulted. The regulation range at p.s.i.g. increased to arange ofO to just over 230 cubic inches per minute, and at p.s.i.g.increased to a range of 0 to 280 cubic inches per minute, as shown bytraces 21 and 22, respectively. The actual characteristics thus followthe expected results as shown from the illustration in FIG. 3, where thehigh gain and regulated pressure range increases with the increasingpressure levels. Further, the fluid consumption is minimal because theregulator requires only twice the value of the flow change which theload encounters and is not related to the total load flow. The maximumflow through nozzle Sand, consequently, also through nozzle 6, is theflow established with the minimum load flow. This in turn establishesthe flow consumption for regulation independently of the total loadflow.

In the present invention, the particular nozzle size and source pressurewill not change the characteristics as long as pressures are maintainedbelow those which might create shock waves and the like which wouldinterfere with the stability of the impact position. The apparatus foroptimum functioning will be restricted to regulated pressures belowpressures at which shock waves are formed, such as, for example, .below40 p.s.i.g. for air. The system can of course operate above such levelif the instability associated with shock waves is acceptable.

Further, as previously noted, the resistor 8 and nozzle 5 function as apressure divider. The normal variations and fluctuations in a practicalpressure source will be correspondingly reflected at nozzles 5 and 6.This results in a percentage change in the regulated load pressure equalto percentage change in the supply pressure. Thus, if the supplypressure in the illustrated embodiment were to increase from 20 to 22p.s.i.g. for any reason, the load pressure would vary by a correspondingpercentage, or 10 percent. Thus if the system were regulating at onepound the load pressure would change by one-tenth of a pound. If theload pressure were being regulated to 10 p.s.i.g., the load pressure,for the above supply variation, would vary by l p.s.i.g.

The operation of the illustrated embodiment of the invention can besummarized as follows. The fluidic resistors 8 and 9 are adjusted toestablish an impact position just outside of the nozzle 5, with aminimum load flow and the desired load pressure. Any increase in theload flow will result in a corresponding decrease in the flow throughthe nozzle 5 to maintain the output pressure constant. Thus, as the loadflow increases, the output pressure would tend to drop as the result ofthe increased flow through the resistor 7. However, any decrease inoutput pressure results in movement of the impact or stagnation pointwith respect to the orifice of the nozzle 5 in a direction into thenozzle orifice, thereby tending to close off the nozzle andsignificantly increasing its impedance. This results in a reversal inthe pressure characteristic to the upstream side of the nozzle 5 toreturn and hold the output pressure at the regulated level. Any increasein output pressure results in an opposite movement of the stagnationpoint to reduce the pressure. The system thus acts as an automatic leakport type control without the necessity for using the conventionalmechanically positioned lid unit which is coupled to a sensing systemfor repositioning of the lid assembly to maintain a constant outputpressure.

The present invention provides a highly acceptable regulation of avariable flow load, which would include varying flow through one loadelement, a plurality of selectively connected load elements or any othersystem coupled to a point between the flow resistance means and theoutlet of the stream forming means which results in a change of flowfrom such point, over a wide range, with the selection and applicationof the system pressure over essentially the complete range of pressuresbelow shock wave pressures. Further, although the system does notdirectly and completely regulate for changes in source pressure, suchchanges are minimized by establishing percentage regulation with respectto source pressure variations.

The present invention thus provides a simple, reliable and inexpensivefluidic pressure regulator which eliminates the necessity for themechanical and the pneumatic type regulators heretofore employed influidic systems. I

Various modes of carrying out the invention are contemplated as beingwithin the scope of the following claims, particularly pointing out anddistinctly claiming the subject matter which is regarded as theinvention.

1. A fluidic' regulated pressure supply system for supplying a regulatedpressure to a variable flow load comprising, a first stream formingmeans including an outlet and a flow resistance means for calibrating afirst stream pressure at said outlet for a minimal flow condition ofsaid load, said load being connected to and supplied from a pointbetween said flow resistance means and said first stream forming meansoutlet and upstream of said outlet, a second stream forming meansmounted in opposed spaced relation to said first stream forming meansfor establishing a second stream, and

of said streams relative to said first stream forming means outlet tovary the impedance of said first stream forming means to maintain thedesired regulated pressure to the load with said varying load flow withrespect to said point.

2. The fluidic regulated pressure supply system of claim 1 wherein saidresistance means is adjustable.

-3. The fluidic regulated pressure supply system of claim 1 wherein saidload is operated at a regulated pressure of the order of hundreths ofpounds per square inch.

4. The fluidic regulated pressure supply system of claim 1 wherein saidregulated pressure is below a level creating shock waves in said firststream forming means.

5. The fluidic regulated pressure supply system of claim 1 wherein saidstream forming means are connected to a source means and are each anozzle means having orifice means establishing said pair of opposedimpacting streams between said nozzle means.

6. The fluidic regulated pressure supply system of claim 5 wherein saidnozzle means establish streams of a pressure below a level sufficient tocreate shock waves.

7. The fluidic regulated pressure supply system of claim 5 wherein saidnozzle means having corresponding orifices are mounted in diametricallyopposed relation.

8. The fluidic regulated pressure supply system of claim 5 wherein saidresistance means includes a first resistor connected between said firstnozzle means and said source means, said system includes a secondresistor connected between said second nozzle means and said sourcemeans, said resistors being selected to establish the impact position ofsaid streams adjacent the orifice of the first nozzle means with aminimum load flow and a selected output pressure.

9. The fluidic regulated pressure supply system of claim 8 wherein saidresistors are adjustable.

10. The fluidic pressure regulator of claim 8 wherein said streamforming means establish streams below a pressure level sufficient tocreate shock waves.

11. A fluidic regulated pressure supply system for supplying a regulatedpressure to a load comprising a pressure source means, a first nozzlehaving an orifice, a second opposed nozzle mounted in diametricallyopposed spaced relation to said first nozzle and having an orificecorresponding to said orifice of the first nozzle, and establishing apair of opposed impacting streams between said nozzle means, a firstflow resistor connecting said first nozzle to said source means, asecond flow resistor connecting said second nozzle to said source means,a variable flow load connected between said first resistor and saidfirst nozzle, said orifice of said first nozzle being selected to carrythe difference between the maximum and the minum load flow, and saidpressure source means and resistors being selected to establish amaximum regulated pressure below the pressure at which shock waves willform.

l l l

1. A fluidic regulated pressure supply system for supplying a regulatedpressure to a variable flow load comprising, a first stream formingmeans including an outlet and a flow resistance means for calibrating afirst stream pressure at said outlet for a minimal flow condition ofsaid load, said load being connected to and supplied from a pointbetween said flow resistance means and said first stream forming meansoutlet and upstream of said outlet, a second stream forming meansmounted in opposed spaced relation to said first stream forming meansfor establishing a second stream, and said first and second formingmeans providing streams of relative strength, one to the other, causingimpacting of said streams between said stream forming means and definingan impacting flow in proximity to the outlet of said first streamforming means wherein varying load flow conditions causes movement ofthe impacting flow of said streams relative to said first stream formingmeans outlet to vary the impedance of said first stream forming means tomaintain the desired regulated pressure to the load with said varyingload flow with respect to said point.
 2. The fluidic regulated pressuresupply system of claim 1 wherein said resistance means is adjustable. 3.The fluidic regulated pressure supply system of claim 1 wherein saidload is operated at a regulated pressure of the order of hundreths ofpounds per square inch.
 4. The fluidic regulated pressure supply systemof claim 1 wherein said regulated pressure is below a level creatingshock waves in said first stream forming means.
 5. The fluidic regulatedpressure supply system of claim 1 wherein said stream forming means areconnected to a source means and are each a nozzle means having orificemeans establishing said pair of opposed impacting streams between saidnozzle means.
 6. The fluidic regulated pressure supply system of claim 5wherein said nozzle means establish streams of a pressure below a levelsufficient to create shock waves.
 7. The fluidic regulated pressuresupply system of claim 5 wherein said nozzle means having correspondingorifices are mounted in diametriCally opposed relation.
 8. The fluidicregulated pressure supply system of claim 5 wherein said resistancemeans includes a first resistor connected between said first nozzlemeans and said source means, said system includes a second resistorconnected between said second nozzle means and said source means, saidresistors being selected to establish the impact position of saidstreams adjacent the orifice of the first nozzle means with a minimumload flow and a selected output pressure.
 9. The fluidic regulatedpressure supply system of claim 8 wherein said resistors are adjustable.10. The fluidic pressure regulator of claim 8 wherein said streamforming means establish streams below a pressure level sufficient tocreate shock waves.
 11. A fluidic regulated pressure supply system forsupplying a regulated pressure to a load comprising a pressure sourcemeans, a first nozzle having an orifice, a second opposed nozzle mountedin diametrically opposed spaced relation to said first nozzle and havingan orifice corresponding to said orifice of the first nozzle, andestablishing a pair of opposed impacting streams between said nozzlemeans, a first flow resistor connecting said first nozzle to said sourcemeans, a second flow resistor connecting said second nozzle to saidsource means, a variable flow load connected between said first resistorand said first nozzle, said orifice of said first nozzle being selectedto carry the difference between the maximum and the minum load flow, andsaid pressure source means and resistors being selected to establish amaximum regulated pressure below the pressure at which shock waves willform.